Top-level pro tennis returned to the United States on Monday, and the Czech Republic's Marie Bouzkova produced an upset at the outset.

Bouzkova knocked off third-seeded Johanna Konta of the United Kingdom 6-4, 6-4 at the Top Seed Open in Lexington, Ky.

The WTA Tour ended its pandemic-induced hiatus last week with an event in Palermo, Italy. The ATP Tour plans to return later this month with the Western Southern Open, moved from Ohio to New York City ahead of the U.S. Open.

Bouzkova picked on Konta's second serve, winning 63 percent of the points. Konta managed to win just 39 percent of the points on Bouzkova's second serve.

Other first-round winners Monday were second-seeded Aryna Sabalenka of Belarus, sixth-seeded Magda Linette of Poland, eighth-seeded Ons Jabeur of Tunisia, Jennifer Brady and Jessica Pagula.

Top-seeded Serena Williams will oppose Bernarda Pera on Tuesday. The winner of that match will meet the winner of a Tuesday match between Serena Williams' sister Venus and Belarus' Victoria Azarenka.

Prague Open

In the only match that finished amid the rain in the Czech Republic, Eugenie Bouchard recorded a 6-0, 6-3 win over eighth-seeded Veronika Kudermetova of Russia.

Bouchard, a 26-year-old Canadian, has been ranked as high as No. 5 in the world, but she is currently No. 332 after a string of poor results. She took advantage of four of her seven break-point opportunities while saving all five of the break points she faced.

Top-seeded Simona Halep of Romania is scheduled for her first match on Tuesday against Slovenia's Polona Hercog.

--Field Level Media